I've wondered the same thing. A couple years ago I was talking to my mother on the phone. She was telling me how her and dad were taking my twin brothers out for a drink on their 21st birthday. I said, "You're celebrating birthdays now?" I was truly shocked. She said, "No, no, no! Of course not. We just want to take them out for their first drink in a controlled environment." 
Yeah right. I said, "Come on mom. Everybody drinks before they turn 21. All of us did it. Do you honestly think this will be their first drink ever?" Paused silence. "Well, I should think so. They aren't legal until this Friday." I imagine her covering her ears with her hands, closing her eyes, and going "Lalalalalalalalala".*sigh*As much as I love my step-mom, she has her head so far into the sand, it's just not even funny.
Yeah right. I said, "Come on mom. Everybody drinks before they turn 21. All of us did it. Do you honestly think this will be their first drink ever?" Paused silence. "Well, I should think so. They aren't legal until this Friday." I imagine her covering her ears with her hands, closing her eyes, and going "Lalalalalalalalala".*sigh*As much as I love my step-mom, she has her head so far into the sand, it's just not even funny.